Filling for gas protection apparatus



Aug.a w 9 19260 IF. KERSCHBAUM FILLING FOR GAS PROTECTION APPARATUSFiled April 13, 1926 4 of the so-called regulated protection ap-'Patented Aug. 10, 1926.

UNITED STATES FFICE.

mums non GAS rnorno'non srrsnarus.

'a ncauo mea A ril 13, 1926, Serial Ira-101,759, and in Germany April11, 1925.

Gases and vaporssuch as hydrocyanic acid and other cyanogen compounds,which are very poisonous but are hardly perceptible by odor, have beenused in combination with irritants and warning materials such aschloropicrin, esters of chloroacetic acid, etc. A very small percentageaddition of irritant .is usually suflicient. For combating noxiousanimals mixtures-are generally used which contain only 1 to 10 parts ofthe admixtures,

which affect the sensory organs and mucous membranes, to 100 partshydrocyanio acid.

The extraordinary excess of the odorless poisonous gas, or that whichhas only a slight odor, brings he danger that the filling of the gasprote tion apparatus, such as a gas mask, maybe exhausted by theabsorption of these toxic gases, although the contents may still beselectively efiective for theremoval of the warning irritants mentioned.Thus the persons wearing the protectiorr apparatus such as gas masks mayrun the risk of inhaling deadly quantities of hydrocyanic acid orsimilar gases, on account of the removal of the irritating action andthe passage of .the toxic gas.

This'ri'sk is lessened by this invention, in that packings are employed,in which agents for the removal of non-irritating gases such as HCN arecombined with separate agents for the removal of irritants. The packingmaterials are proportioned so that the irritant absorbent will becomesaturated before the toxic gas absorbent becomes useless.

It is known that basic zinc carbonate .or other basic metallic salts,mixed with a material such as infusorial earth, have been used ascombining agents for hydrocyanic acid. Active adsorption agents,especially active carbon, are used as binding agents for irritants suchas chloropicrin, ester of chloroacetic acid,etc. The process, accordingto this; invention, consists in using the chemical binding agentsi-n themost concentrated form in which. they are active. -This is done withoutdiluting more than is'necessary, so that large quantities of thecarrying material can'be used. Strongly active binding agents such ascaustic alkali may be used in place of the basic zinc carbonate. Whencaustic alkali is used an arrangement is made so that-the exhaled airdoes not pass thru the packing. This may be attained byuse paratus..Also the agents for binding the irritant-are so chosen-'and appliedinsuch a way that theywill be exhausted before the chemical binding agentfor the hydrocyanic acid becomes ineffective.

It has been shown that the combination of a layer of basic zinccarbonate as a chemical binding material for hydrocyanic' acid andactive carbon as an agent for binding the irritant requires a veryconsiderable thickness of basic zinc carbonate layer and only aproportionally small; thickness of layer of actlve carbon. This showscertain difiiculties, as there is a danger, in using. very diattained byproviding suitable adsorbing materials. A preferable way is'to use, in-

stead of highlyactive carbon, that ofia reduced degree of adsorption.The latter can thus be used in a layer of greater thickness.

For this purpose, the preparation or activation otthe active carbon maybe undertaken under conditions which prevent the formation of highlyactive carbon. This maybe done by using a suitable supply of air duringor after the caibonization; or one, may proceed with the usual activecharcoal of high capacity of adsorption and adjust its,

activity to a desired degree by suitable treat ment, e. with water orsteam or suitable salt solutions, such as potassium carbonate or zincchloride solutions.

As it' is desirable to so measure the total' strength of the packingthat the passage of resplratory air will not be obstructedsubstantially, the combination of both of the previously specified waysis recommended;

namely, the use of a highly efiicientbinding agent for'hydrocyanic acidin proportionally small thickness of layer in combination with the useof proportionally'weakly active'binding agents for the irritants. Thelatter may then be used in proportionally greater thickness f layer. Thesize of the respective layers of the binding material. reacting w1t hthe poisonous ases such as hydro'cyamc acid and the a sorbent for theirritant'de-- pends on the one hand upon the eiiiciency of the absorbingand reacting materials to retain-the poisonous gases and 'theirntants.These qualities are, as stated above, subject to the activity of thecharcoal and to the concentration of the salts which serve to bind thepoisonous gas They-depend on the other hand upon the ratio with whichthe poisonous gas and the irritant are present in the gas mixture to beused. The fol lowing example refers to a gas mixture which contains 10parts chloropicrin to 100 parts hydrocyanic acid; but I want it to beunderstood that I do not restrict myself either to the ratio of gasespresent in the gas mixture I have mentioned above, or to the specialconcentration of the binding material nor to the retentivity of activecarbon indicated.

A cylindrical gas mask canister 10 cm. in diameter is filled as shown inthe attached drawing, Fig. 1. At the air entrance 1 is first placed ascreen distributor 2. On this screen distributor is placed a layer ofactive carbon 3. The thickness of the carbon layer is 2 cm. and shouldbe capable of retaining 0.8 grams irritant by either specially selectingthe active carbon accordingly or treating it preliminarily with steam orsuitable salt solutions such as sodium carbonate or zinc chloride 50that a layer of the active carbon 1 cm. thick will retain 0.4 gramirritant. On the layer of active carbon 3 is placed a layer 4 for theabsorption of hydrocyanic acid 5 to 6 centimeters thick and consistingof a granular material suchas pumice treated with basic zinc carbonate.The concentration of the granular inert mass in relation to the reactingbasic zinc carbonate ought to be such that a layer 1 cm. thick of thereadily prepared adsorbent should retain 2.5 to 3 grams of hydrocyanicacid.

On the top of the layer 4 is placed another screen distributor 5. 6 isthe screw by means of which the canister is fixed in the gas mask.

What I claim is:

1. A filling for gas protection apparatus which comprises a layer ofadsorbent for irritants and a layer of adsorbent for poison-' ous gasesthe adsorption power of the layers being proportioned in such a way asregards thickness and adsorbing quality that the adsorbent layer for theirritant becomes exhausted before the adsorbent layer for the poisonousgases.

' 2. A filling for gas protection apparatus which comprises a layer ofadsorbent for irritants and a layer of adsorbent for poisonous gases theadsorption power of the layers being proportioned in such a way asregards thickness and adsorbing quality that the poisonous gasesarestill absorbed by the corresponding layer whilst the irritant permeatesalready the exhausted absorbent.

3. A filling for gas protection apparatus which comprises a layer ofactive carbon and. a layer of adsorbent for poisonous gases theabsorptive power of the layers being proportioned in such a way asregards thickness and absorbing quality that the active carbon becomesexhausted before the absorbent layer for the poisonous gases.

4. A filling for gas protection apparatus which comprises a layer ofactive carbon and a layer of absorbent for hydrocyanic acid gas theabsorptive power of the layers being proportioned in such a way asregards thickness and absorption quality that the hydrocyanic acid isstill absorbed when the irritant permeates already the exhaustedabsorbent.

5. A filling for gas protection apparatus which comprises a layer ofactive carbon and a layer of absorbent containing basic zinc carbonatethe absorptive power of the layers being proportioned in such a way asregards thickness and absorption quality that the hydrocyanic acid isstill absorbed when the irritant permeates already the exhaustedabsorbent.

6. A filling for gas protection apparatus which comprises a layer ofactive carbon and a layer of absorbent containing basic zinc carbonatethe thickness and concentration of the latter layer and the retentivityand the thickness of the former being proportioned in such a way thatthe hydrocyanic acid is still absorbed when the irritant permeatesalready the exhausted active charcoal.

7. A filling for gas protection apparatus which comprises a layer ofactive carbon and a layer of absorbent'for hydrocyanic acid thethickness of the active carbon layer being two or three times shorterthan the absorbent layer for hydrocyanic acid when the absorpa tivepower and retentivity of the active carbon is 0.4 grams irritant for 75cb. cm. of the absorbent and the absorptive power and retentivity of theabsorbent layer for hydrocyanic acid is 2.5 to 3 grams of hydrocyanicacid for 75 ch. cm. of absorbent, the amount of irritant in the gasmixture being 10 parts to parts hydrocyanic acid.

8. A filling for gas protection apparatus which comprises a layer ofactive carbon and a layer of absorbent containing basic zinc carbonatethe thickness of the active carbon March A. D. 1926.

FRIEDRICH KIjlRSCHBAUM.

